Dimethylformamide → (S)-7-bromo-3-(neopentyloxy)-5'H-spiro[chromeno[2,3-b]pyridine-5,4'-oxazol]-2'-amine

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a solution of (S)-2′-amino-7-bromo-5′H-spiro[chromeno[2,3-b]pyridine-5,4′-oxazol]-3-ol (390 mg, 1.120 mmol) in DMF (4481 μL, 1.120 mmol) in a sealed tube was added cesium carbonate (912 mg, 2.80 mmol). After stirring for 1 minute neopentyl iodide (223 μL, 1.680 mmol) was added, the reaction vessel was sealed and heated at 100° C. for 2.5 hours. Reaction was cooled to RT to prevent over alkylation. The reaction was diluted with water (25 mL) and 10 mL of ethyl acetate and stirred for 30 minutes before being poured into a separatory funnel containing ethyl acetate (100 mL) and water (250 mL). The layers were separated and the aqueous layer was extracted with ethyl acetate (3×50 mL). The aqueous layer was then extracted with DCM (3×50 mL). The organic layers were each washed with water and then brine, at which point all the organics were combined, dried over sodium sulfate, filtered and concentrated in vacuo to provide a brown foam that was purified by silica gel chromatography (Redi-Sep pre-packed silica gel column (40 g), 0-10% methanol in methylenechloride with 0.1% ammonium hydroxide) to provide (S)-7-bromo-3-(neopentyloxy)-5′H-spiro[chromeno[2,3-b]pyridine-5,4′-oxazol]-2′-amine as a yellow solid. Step 2: A sealable tube was charged with (S)-7-bromo-3-(neopentyloxy)-5′H-spiro[chromeno[2,3-b]pyridine-5,4′-oxazol]-2′-amine (75 mg, 0.179 mmol), copper iodide (3.38 mg, 0.018 mmol), tetrakis(triphenylphosphine)palladium (20.53 mg, 0.018 mmol). To this mixture was added DMF (355 μL, 0.178 mmol), diisopropylamine (498 μL, 3.55 mmol) and trimethyl((3-methyloxetan-3-yl)ethynyl)silane (90 mg, 0.533 mmol). The tube was flushed with argon, sealed and heated to 90° C. for 12 hours. The reaction was diluted with water (100 mL) and poured into a separatory funnel containing ethyl acetate (50 mL). The layers were separated and the aqueous layer was extracted with ethyl acetate (2×50 mL). The combined organic layers were washed with water and then brine, dried over sodium sulfate, filtered and concentrated in vacuo to provide a brown oil that was purified by silica gel chromatography (Redi-Sep pre-packed silica gel column (12 g), 0-10% methanol in methylenechloride with 0.1% ammonium hydroxide) to provide (S)-7-((3-methyloxetan-3-yl)ethynyl)-3-(neopentyloxy)-5′H-spiro[chromeno[2,3-b]pyridine-5,4′-oxazol]-2′-amine as a yellow solid.

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